In general, the invention is concerned with grain sorting techniques and, more particularly, with methods to sort grains in order to produce gluten free oats.
Sensitivity to gluten is estimated at afflicting up to 2% of the population. In fact, based on the increased awareness of Celiac disease and gluten intolerance, gluten levels in certain foods can be a limiting factor in consumption. Oats themselves do not contain gluten. However, oats cultivated in North America, Europe and even other parts of the world are commonly contaminated by gluten containing foreign grains, including wheat, barley, rye and triticale. These foreign grains typically exhibit about 14% by weight protein, with 40% of the protein being attributable to gluten such that approximately 5.6% by weight of the grains is gluten. This contamination is commonly known to come from various sources, mainly from the rotation of small grain crops on the same land, with residual contaminating seeds germinating with a seeded oat crop. In addition, contamination from other grains which are harvested, transported, stored and merchandized in common with oats is a contributing factor. As a result, it is not uncommon to find from 0.5% to 5.0% of these other grains mixed with commercially marketed oats. Therefore, absent dedicating land, harvesting equipment, transporting vehicles, storage units, packaging and production facilities, and the like only for use in connection with oats, cross contamination is inevitable.
Although the federal government has not finalized rules for labeling products “gluten-free”, the American regulations will likely be similar to the Codex rules established in Europe, which stipulate a maximum of 20 ppm gluten in “gluten-free” food products. Based on draft proposals from the United States Food and Drug Administration, oats will continue to be eligible for gluten-free labeling as long as they are substantially free of foreign seeds. With this in mind, separating oats from foreign grains and other contaminants is required if oat products are to be produced to mandated gluten levels.
Known grain sorting techniques typically rely on mechanical or optical systems. Mechanical systems are considered advantageous generally based on their simplicity and cost benefits. However, simply put, previous attempts to employ mechanical sorting machines have failed to consistently deliver a high yield of oats without undesirably high levels of gluten contaminants. Optical systems generally employ multiple cameras to view grain falling toward a grain rejection mechanism. In some machines, duplicate optical units are positioned on opposite sides of a sorter to provide simultaneous images of opposing sides of the grains. In general, optical sorters have higher associated costs and known optical sorters also have not been sufficiently effective in achieving the reduced gluten levels desired in accordance with the invention. Therefore, there is seen to exist a need to provide a method for effectively and efficiently decontaminating oat grains in order to produce a high yield of gluten-free oats useable for various purposes, particularly as an oat ingredient in the production of various food products, including cereal and granola.